Method and apparatus for transmitting and receiving channel state information in communication system

Abstract

A method of a terminal may comprise: receiving a reference signal from a base station; generating a precoding vector based on the reference signal; generating a low-dimensional precoding vector by performing dimensionality reduction transformation on the precoding vector; quantizing the low-dimensional precoding vector; and transmitting the quantized low-dimensional precoding vector to the base station.

What is claimed is: 
     
         1 . A method of a terminal, comprising:
 receiving a reference signal from a base station;   generating a precoding vector based on the reference signal;   generating a low-dimensional precoding vector by performing dimensionality reduction transformation on the precoding vector;   quantizing the low-dimensional precoding vector; and   transmitting the quantized low-dimensional precoding vector to the base station.   
     
     
         2 . The method according to  claim 1 , further comprising: receiving information on principal component vectors from the base station, wherein in the generating of the low-dimensional precoding vector, the low-dimensional precoding vector is generated by performing dimensionality reduction transformation on the precoding vector through a principal component analysis scheme using the principal component vectors. 
     
     
         3 . The method according to  claim 2 , wherein information on the principal component vectors is received from the base station in a form of higher layer configuration parameter(s). 
     
     
         4 . The method according to  claim 1 , wherein in the generating of the low-dimensional precoding vector, the low-dimensional precoding vector is generated by performing dimensionality reduction transformation on the precoding vector through an independent component analysis scheme. 
     
     
         5 . The method according to  claim 1 , wherein the quantizing of the low-dimensional precoding vector comprises:
 transforming elements of the low-dimensional precoding vector by applying a distribution function; and   quantizing the elements transformed through the distribution function.   
     
     
         6 . The method according to  claim 5 , wherein the distribution function is one of a cumulative distribution function (CDF) function, a CDF function approximated as a normal distribution function, or a normal distribution function. 
     
     
         7 . The method according to  claim 5 , wherein in the quantizing of the elements transformed through the distribution function, the quantizing is performed using at least one of a uniform quantization scheme, a scalar quantization scheme, or a quantization scheme using a Lloyd Max quantizer. 
     
     
         8 . The method according to  claim 1 , wherein in the quantizing of the low-dimensional precoding vector, elements of all dimensions of the low-dimensional precoding vector or elements of each dimension of the low-dimensional precoding vector are quantized. 
     
     
         9 . The method according to  claim 8 , wherein when the elements of each dimension of the low-dimensional precoding vector are quantized, a bit length is maintained to be identical between dimensions or decreases as the dimension increases. 
     
     
         10 . The method according to  claim 8 , wherein when the elements of each dimension of the low-dimensional precoding vector are quantized, a bit length for each dimension is determined according to importance based on an explained variance of each dimension. 
     
     
         11 . A method of a terminal, comprising:
 receiving, from a base station, information on reporting target subbands among subbands of a use band;   receiving a reference signal from the base station;   generating precoding vectors for the reporting target subbands based on the reference signal;   generating low-dimensional precoding vectors by performing dimensionality reduction transformation on the precoding vectors;   quantizing the low-dimensional precoding vectors; and   transmitting the quantized low-dimensional precoding vectors to the base station.   
     
     
         12 . The method according to  claim 11 , wherein the information on the reporting target subbands may be one of: information indicating all of the subbands of the use band as the reporting target subbands, information indicating subbands expected to be used among the subbands of the use band as the reporting target subbands, information indicating an index of a starting subband among the subbands of the use band and an interval between subbands, or information indicating a number of the reporting target subbands and an interval between subbands. 
     
     
         13 . The method according to  claim 11 , wherein the generating of the low-dimensional precoding vectors comprises:
 decomposing the precoding vectors for the reporting target subbands into a wideband precoding vector and a residual precoding vector for each subband;   generating a wideband low-dimensional precoding vector from among the low-dimensional precoding vectors by performing dimensionality reduction transformation on the wideband precoding vector using first principal component vectors; and   generating a low-dimensional precoding vector for each subband from among the low-dimensional precoding vectors by performing dimensionality reduction transformation on the residual precoding vector for each subband using second principal component vectors.   
     
     
         14 . The method according to  claim 11 , wherein the generating of the low-dimensional precoding vectors comprises:
 generating antenna-domain low-dimensional precoding vectors from among the low-dimensional precoding vectors by performing dimensionality reduction transformation on the precoding vectors for the reporting target subbands using antenna-domain principal component vectors; and   generating subband-domain low-dimensional precoding vectors from among the antenna-domain low-dimensional precoding vectors by performing dimensionality reduction transformation on the antenna-domain low-dimensional precoding vectors using subband-domain principal component vectors.   
     
     
         15 . A method of a base station, comprising:
 transmitting a reference signal to a terminal;   receiving a quantized low-dimensional precoding vector based on the reference signal from the terminal;   generating a low-dimensional precoding vector by dequantizing the quantized low-dimensional precoding vector; and   reconstructing a precoding vector from the low-dimensional precoding vector.   
     
     
         16 . The method according to  claim 15 , wherein in the reconstructing of the original precoding vector, the precoding vector is reconstructed from the low-dimensional precoding vector in an inverse principal component analysis scheme. 
     
     
         17 . The method according to  claim 15 , further comprising: restoring an original precoding vector from the reconstructed precoding vector by using an artificial neural network. 
     
     
         18 . The method according to  claim 17 , wherein the artificial neural network is one of a fully-connected neural network, a multi-layer perceptron, a convolutional neural network, or a transformer. 
     
     
         19 . The method according to  claim 15 , wherein the quantized low-dimensional precoding vector is received together with information on a number of reduced dimensions and information on a bit length for each dimension, and the low-dimensional precoding vector is generated through dequantization on the quantized low-dimensional precoding vector using the information on the number of reduced dimensions and the information on the bit length.